Imaging of histological samples is generally undertaken on sections or slices of sample that have been mounted on slides and then stained to reveal features within each sample slice. However distortion of the slices occurs, for example due to shrinkage, causing a degree of misalignment between successive slices and complicating analysis of the features within the sample.
Fiducial markers have been introduced into the sample prior to sectioning so that the distortion can be compensated for. However the sample preparation and subsequent image analysis is very time consuming and difficult to automate.
An episcopic imaging method using bright field illumination and surface staining has been used to reveal tissue structure of a sample, with the uppermost surface of the sample being imaged as successive sections are in turn cut and removed. By imaging the upper surface of the sample for around 1/100th second before removing a thin slice to reveal the next surface of the sample, distortion effects between the different images are avoided. However the resolution of features within the sample tissue is limited due to penetration of the stain, as the depth of penetration of the stain restricts how thinly the sample can be sliced.
It is an aim of the present invention to provide a method and related apparatus for imaging a histological sample that allows improved resolution of features within the sample.